BULLY OF AN ANT MEETS ITS MATCH

Inside a hapless fire ant, a tiny maggot is growing, feeding on the internal fluids and organs of the stinging insect. The maggot migrates to the ant's head, which soon falls off because of an enzyme released by the larval fly. A metamorphosis takes place inside the head, and a smaller-than-flea-size phorid fly begins another generation by crawling out through the dead ant's mouth.

It's not science fiction or a horror movie. Scientists have released millions of the little decapitating flies along with other controls to put the bite on Florida's loathsome fire ants.

"It is not possible to eradicate fire ants in the United States short of sterilizing the whole South -- and that would be pretty extreme," said Sanford Porter, lead scientist of the U.S. Department of Agriculture's Agricultural Research Service.

"In South America, they are one-fifth to one-tenth the density here, and we think it's [because of] the natural enemies," he said of fire ants.

Fire ants came to the United States about 70 years ago from South America. Without natural enemies, they quickly spread throughout the South and are in 12 states and Puerto Rico, infesting more than 320 million acres. About 40 percent of the people in infested areas are stung each year, federal researchers say.

Fire ants fervently defend their nests from intruders, crawling on victims by the hundreds -- sometimes thousands -- when disturbed. In unison, thought to be triggered by a pheromone, each ant delivers burning stings over and over. A white pustule forms on the site of the sting, which will heal in 10 to 14 days. A protein in the sting can be fatal for people allergic to bee and wasp venom.

"Every year, ants cost $5 [billion] to $6 billion in losses, between medical treatment and damaging electronic equipment," said Phil Koehler, professor of entomology at the University of Florida in Gainesville. "They kill livestock and devastate the ecological environment, ground-nesting birds are destroyed, and sea turtles hatching out of eggs are killed."

Scientists, curious why there were fewer fire ants in their natural range, discovered the phorid fly along with other natural controls. The flies passed rigorous testing to ensure they would not cause problems for native plants and animals. The first groups were released in 1997 around Gainesville and established themselves. Since then, phorid flies have been released in other locations, and each group expands its territory by 10 to 20-plus miles a year. The phorid implants one egg at a time into a fire ant's body through a stinger on its tail.

The program to use biological controls is run by the Agricultural Research Service. The program's goal is to use baits and bio-controls to achieve a sustained 80 percent reduction of fire ants and save at least $4 billion in control costs and damages. The natural controls are meant to reduce the use of chemicals and help restore nature's balance.

At the fly-rearing facility in Gainesville, George Schneider, biological administrator, said more than 2 million flies were raised last year, and colonies have been established in all the major releases in Florida. Researchers say the program is working.

Last November, the flies were released in a field in the Christmas area of east Orange County. They are expected to blanket Orlando within a year or two. Releases usually involve about 10,000 flies over a nine- to 10-day period.

The flies are effective: Not only do they kill the host ant, but ants remaining in the mound hide to avoid attack, and the colony is weakened and starves.

But don't think there will be a day you can run to the garden store and buy phorid flies. They are expensive to raise and will remain in the hands of federal and university researchers.

To date, two species of the phorid fly have been released and others are under consideration. Each species attacks a specific size fire ant and is active only part of the day. It is a challenge for the scientists in the field to monitor flies, which are the size of an ant's head and move fast as they hover close to fire-ant mounds.

Another biological control being used is a virus, Thelohania fire-ant disease. When a colony is infected, the queens produce 90 percent fewer eggs and only a few ants survive. Strong ants from other colonies invade the weakened colony and adopt the diseased larvae, spreading the disease to the invading ants.

While the disease is effective, it is slower to spread than the phorid flies.

"We're bringing the numbers down where people can live with them," Koehler said.

While the phorid fly will not eliminate fire ants, they, along with other controls, can greatly reduce their numbers.

"It takes a long time to see reductions in fire ant populations as a result of releasing controls," Koehler said.